2.1. Dosing in Adults

The recommended dose of doxepin hydrochloride tablets for adults is 6 mg once daily. A 3 mg once daily dose may be appropriate for some patients, if clinically indicated.

2.2. Dosing in the Elderly

The recommended starting dose of doxepin hydrochloride tablets in elderly patients (≥ 65 years old) is 3 mg once daily. The daily dose can be increased to 6 mg, if clinically indicated.

2.3. Administration

Doxepin hydrochloride tablets should be taken within 30 minutes of bedtime.

To minimize the potential for next day effects, doxepin hydrochloride tablets should not be taken within 3 hours of a meal [see Clinical Pharmacology (12.3)].

The total doxepin hydrochloride tablets dose should not exceed 6 mg per day.

4.1. Hypersensitivity

Doxepin hydrochloride tablets are contraindicated in individuals who have shown hypersensitivity to doxepin HCl, any of its inactive ingredients, or other dibenzoxepines.

4.2. Co-administration with Monoamine Oxidase Inhibitors (MAOIs)

Serious side effects and even death have been reported following the concomitant use of certain drugs with MAO inhibitors. Do not administer doxepin hydrochloride tablets if patient is currently on MAOIs or has used MAOIs within the past two weeks. The exact length of time may vary depending on the particular MAOI dosage and duration of treatment.

4.3. Glaucoma and Urinary Retention

Doxepin hydrochloride tablets are contraindicated in individuals with untreated narrow angle glaucoma or severe urinary retention.

5.1. Need to Evaluate for Comorbid Diagnoses

Because sleep disturbances may be the presenting manifestation of a physical and/or psychiatric disorder, symptomatic treatment of insomnia should be initiated only after careful evaluation of the patient. The failure of insomnia to remit after 7 to 10 days of treatment may indicate the presence of a primary psychiatric and/or medical illness that should be evaluated. Exacerbation of insomnia or the emergence of new cognitive or behavioral abnormalities may be the consequence of an unrecognized psychiatric or physical disorder. Such findings have emerged during the course of treatment with hypnotic drugs.

5.2. Abnormal Thinking and Behavioral Changes

Complex behaviors such as “sleep-driving” (i.e., driving while not fully awake after ingestion of a hypnotic, with amnesia for the event) have been reported with hypnotics. These events can occur in hypnotic-naive as well as in hypnotic-experienced persons. Although behaviors such as “sleep-driving” may occur with hypnotics alone at therapeutic doses, the use of alcohol and other CNS depressants with hypnotics appears to increase the risk of such behaviors, as does the use of hypnotics at doses exceeding the maximum recommended dose. Due to the risk to the patient and the community, discontinuation of doxepin hydrochloride tablets should be strongly considered for patients who report a “sleep-driving” episode. Other complex behaviors (e.g., preparing and eating food, making phone calls, or having sex) have been reported in patients who are not fully awake after taking a hypnotic. As with “sleep-driving”, patients usually do not remember these events. Amnesia, anxiety and other neuro-psychiatric symptoms may occur unpredictably.

5.3. Suicide Risk and Worsening of Depression

In primarily depressed patients, worsening of depression, including suicidal thoughts and actions (including completed suicides), has been reported in association with the use of hypnotics.

Doxepin, the active ingredient in doxepin hydrochloride tablets, is an antidepressant at doses 10- to 100-fold higher than in doxepin hydrochloride tablets. Antidepressants increased the risk compared to placebo of suicidal thinking and behavior (suicidality) in children, adolescents, and young adults in short-term studies of major depressive disorder (MDD) and other psychiatric disorders. Risk from the lower dose of doxepin in doxepin hydrochloride tablets can not be excluded.

It can rarely be determined with certainty whether a particular instance of the abnormal behaviors listed above is drug induced, spontaneous in origin, or a result of an underlying psychiatric or physical disorder. Nonetheless, the emergence of any new behavioral sign or symptom of concern requires careful and immediate evaluation.

5.4. CNS Depressant Effects

After taking doxepin hydrochloride tablets, patients should confine their activities to those necessary to prepare for bed. Patients should avoid engaging in hazardous activities, such as operating a motor vehicle or heavy machinery, at night after taking doxepin hydrochloride tablets, and should be cautioned about potential impairment in the performance of such activities that may occur the day following ingestion.

When taken with doxepin hydrochloride tablets, the sedative effects of alcoholic beverages, sedating antihistamines, and other CNS depressants may be potentiated [see Warnings and Precautions (5.2) and Drug Interactions (7.3, 7.4)]. Patients should not consume alcohol with doxepin hydrochloride tablets [see Warnings and Precautions (5.2) and Drug Interactions (7.3)]. Patients should be cautioned about potential additive effects of doxepin hydrochloride tablets used in combination with CNS depressants or sedating antihistamines [see Warnings and Precautions (5.2) and Drug Interactions (7.4)].

6.1. Clinical Trials Experience

The pre-marketing development program for doxepin hydrochloride tablets included doxepin HCl exposures in 1017 subjects (580 insomnia patients and 437 healthy subjects) from 12 studies conducted in the United States. 863 of these subjects (580 insomnia patients and 283 healthy subjects) participated in six randomized, placebo-controlled efficacy studies with doxepin hydrochloride tablets doses of 1 mg, 3 mg, and 6 mg for up to 3-months in duration.

Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice. However, data from the doxepin hydrochloride tablets studies provide the physician with a basis for estimating the relative contributions of drug and non-drug factors to adverse reaction incidence rates in the populations studied.

6.2. Studies Pertinent to Safety Concerns for Sleep-promoting Drugs

6.3. Other Reactions Observed During the Pre-marketing Evaluation of Silenor

Doxepin hydrochloride tablets were administered to 1017 subjects in clinical trials in the United States. Treatment-emergent adverse reactions recorded by clinical investigators were standardized using a modified MedDRA dictionary of preferred terms. The following is a list of MedDRA terms that reflect treatment-emergent adverse reactions reported by subjects treated with doxepin hydrochloride tablets.

Adverse reactions are further categorized by body system and listed in order of decreasing frequency according to the following definitions: Frequent adverse reactions are those that occurred on one or more occasions in at least 1/100 subjects; Infrequent adverse reactions are those that occurred in fewer than 1/100 subjects and more than 1/1000 subjects. Rare adverse reactions are those that occurred in fewer than 1/1000 subjects. Adverse reactions that are listed in Table 1 are not included in the following listing of frequent, infrequent, and rare AEs.

Blood and Lymphatic System Disorders: Infrequent: anemia; Rare: thrombocythemia.

Cardiac Disorders: Rare: atrioventricular block, palpitations, tachycardia, ventricular extrasystoles.

Ear and Labyrinth Disorders: Rare: ear pain, hypoacusis, motion sickness, tinnitus, tympanic membrane perforation.

Eye Disorders: Infrequent: eye redness, vision blurred; Rare: blepharospasm, diplopia, eye pain, lacrimation decreased.

Gastrointestinal Disorders: Infrequent: abdominal pain, dry mouth, gastroesophageal reflux disease, vomiting; Rare: dyspepsia, constipation, gingival recession, haematochezia, lip blister.

General Disorders and Administration Site Conditions: Infrequent: asthenia, chest pain, fatigue; Rare: chills, gait abnormal, edema peripheral.

Hepatobiliary Disorders: Rare: hyperbilirubinemia.

Immune System Disorders: Rare: hypersensitivity.

Infections and Infestations: Infrequent: bronchitis, fungal infection, laryngitis, sinusitis, tooth infection, urinary tract infection, viral infection; Rare: cellulitis staphylococcal, eye infection, folliculitis, gastroenteritis viral, herpes zoster, infective tenosynovitis, influenza, lower respiratory tract infection, onychomycosis, pharyngitis, pneumonia.

Injury, Poisoning and Procedural Complications: Infrequent: back injury, fall, joint sprain; Rare: bone fracture, skin laceration.

Investigations: Infrequent: blood glucose increased; Rare: alanine aminotransferase increased, blood pressure decreased, blood pressure increased, electrocardiogram ST-T segment abnormal, electrocardiogram QRS complex abnormal, heart rate decreased, neutrophil count decreased, QRS axis abnormal, transaminases increased.

Metabolism and Nutrition Disorders: Infrequent: anorexia, decreased appetite, hyperkalemia, hypermagnesemia, increased appetite; Rare: hypokalemia.

Musculoskeletal and Connective Tissue Disorders: Infrequent: arthralgia, back pain, myalgia, neck pain, pain in extremity; Rare: joint range of motion decreased, muscle cramp, sensation of heaviness.

Neoplasms Benign, Malignant and Unspecified (Including Cysts and Polyps): Rare: lung adenocarcinoma stage I, malignant melanoma.

Nervous System Disorders: Frequent: dizziness; Infrequent: dysgeusia, lethargy, parasthesia, syncope; Rare: ageusia, ataxia, cerebrovascular accident, disturbance in attention, migraine, sleep paralysis, syncope vasovagal, tremor.

Psychiatric Disorders: Infrequent: abnormal dreams, adjustment disorder, anxiety, depression; Rare: confusional state, elevated mood, insomnia, libido decreased, nightmare.

Reproductive System and Breast Disorders: Rare: breast cyst, dysmenorrhea.

Renal and Urinary Disorders: Rare: dysuria, enuresis, hemoglobinuria, nocturia.

Respiratory, Thoracic and Mediastinal Disorders: Infrequent: nasal congestion, pharyngolaryngeal pain, sinus congestion, wheezing; Rare: cough, crackles lung, nasopharyngeal disorder, rhinorrhea, dyspnea.

Skin and Subcutaneous Tissue Disorders: Infrequent: skin irritation; Rare: cold sweat, dermatitis, erythema, hyperhidrosis, pruritis, rash, rosacea.

Surgical and Medical Procedures: Rare: arthrodesis.

Vascular Disorders: Infrequent: pallor; Rare: blood pressure inadequately controlled, hematoma, hot flush.

In addition, the reactions below have been reported for other tricyclics and may be idiosyncratic (not related to dose).

Allergic: photosensitization, skin rash.

Hematologic: agranulocytosis, eosinophilia, leukopenia, purpura, thrombocytopenia.

7.1. Cytochrome P450 Isozymes

Doxepin hydrochloride is primarily metabolized by hepatic cytochrome P450 isozymes CYP2C19 and CYP2D6, and to a lesser extent, by CYP1A2 and CYP2C9. Inhibitors of these isozymes may increase the exposure of doxepin. Doxepin hydrochloride is not an inhibitor of any CYP isozymes at therapeutically relevant concentrations. The ability of doxepin hydrochloride to induce CYP isozymes is not known.

7.2. Cimetidine

Doxepin hydrochloride exposure is doubled with concomitant administration of cimetidine, a nonspecific inhibitor of CYP isozymes. A maximum dose of 3 mg is recommended in adults and elderly when cimetidine is co-administered with doxepin hydrochloride tablets [see Clinical Pharmacology (12.4)].

7.3. Alcohol

When taken with doxepin hydrochloride tablets, the sedative effects of alcohol may be potentiated [see Warnings and Precautions (5.2, 5.4)].

7.4. CNS Depressants and Sedating Antihistamines

When taken with doxepin hydrochloride tablets, the sedative effects of sedating antihistamines and CNS depressants may be potentiated [see Warnings and Precautions (5.2, 5.4)].

7.5. Tolazamide

A case of severe hypoglycemia has been reported in a type II diabetic patient maintained on tolazamide (1 g/day) 11 days after the addition of oral doxepin (75 mg/day).

8.1 Pregnancy

8.2 Labor and Delivery

The effects of doxepin hydrochloride tablets on labor and delivery in pregnant women are unknown.

8.3 Nursing Mothers

Doxepin is excreted in human milk after oral administration. There has been a report of apnea and drowsiness occurring in a nursing infant whose mother was taking the higher dose of doxepin used to treat depression. Caution should be exercised when doxepin hydrochloride tablets are administered to nursing women.

8.4 Pediatric Use

The safety and effectiveness of doxepin hydrochloride tablets in pediatric patients have not been evaluated.

8.5 Geriatric Use

A total of 362 subjects who were ≥ 65 years and 86 subjects who were ≥ 75 years received doxepin hydrochloride tablets in controlled clinical studies. No overall differences in safety or effectiveness were observed between these subjects and younger adult subjects. Greater sensitivity of some older individuals cannot be ruled out.

Sleep-promoting drugs may cause confusion and over-sedation in the elderly. A starting dose of 3 mg is recommended in this population and evaluation prior to considering dose escalation is recommended [see Dosage and Administration (2.2)].

8.6 Use in Patients with Hepatic Impairment

Patients with hepatic impairment may display higher doxepin concentrations than healthy individuals. Initiate doxepin hydrochloride tablets treatment with 3 mg in patients with hepatic impairment and monitor closely for adverse daytime effects [see Clinical Pharmacology (12.5)].

8.7 Use in Patients with Sleep Apnea

Doxepin hydrochloride tablets have not been studied in patients with obstructive sleep apnea. Since hypnotics have the capacity to depress respiratory drive, precautions should be taken if doxepin hydrochloride tablets are prescribed to patients with compromised respiratory function. In patients with severe sleep apnea, doxepin hydrochloride tablets are ordinarily not recommended for use.

9.1 Controlled Substance

Doxepin is not a controlled substance.

9.2 Abuse

Doxepin is not associated with abuse potential in animals or in humans. Physicians should carefully evaluate patients for history of drug abuse and follow such patients closely, observing them for signs of misuse or abuse of doxepin (e.g., incrementation of dose, drug-seeking behavior).

9.3 Dependence

In a brief assessment of adverse events observed during discontinuation of doxepin following chronic administration, no symptoms indicative of a withdrawal syndrome were observed. Thus, doxepin does not appear to produce physical dependence.

10.1. Signs and Symptoms of Excessive Doses

The following adverse effects have been associated with use of doxepin at doses higher than 6 mg.

Anticholinergic Effects: constipation and urinary retention.

Central Nervous System: disorientation, hallucinations, numbness, paresthesias, extrapyramidal symptoms, seizures, tardive dyskinesia.

Cardiovascular: hypotension.

Gastrointestinal: aphthous stomatitis, indigestion.

Endocrine: raised libido, testicular swelling, gynecomastia in males, enlargement of breasts and galactorrhea in the female, raising or lowering of blood sugar levels, and syndrome of inappropriate antidiuretic hormone secretion.

Other: tinnitus, weight gain, sweating, flushing, jaundice, alopecia, exacerbation of asthma, and hyperpyrexia (in association with chlorpromazine).

10.2. Signs and Symptoms of Critical Overdose

Manifestations of doxepin critical overdose include: cardiac dysrhythmias, severe hypotension, convulsions, and CNS depression including coma. Electrocardiogram changes, particularly in QRS axis or width, are clinically significant indicators of tricyclic compound toxicity. Other signs of overdose may include, but are not limited to: confusion, disturbed concentration, transient visual hallucinations, dilated pupils, agitation, hyperactive reflexes, stupor, drowsiness, muscle rigidity, vomiting, hypothermia, hyperpyrexia.

10.3. Recommended Management

As management of overdose is complex and changing, it is recommended that the physician contact a poison control center for current information on treatment. In addition, the possibility of a multiple drug ingestion should be considered.

If an overdose is suspected, an ECG should be obtained and cardiac monitoring should be initiated immediately. The patient’s airway should be protected, an intravenous line should be established, and gastric decontamination should be initiated. A minimum of six hours of observation with cardiac monitoring and observation for signs of CNS or respiratory depression, hypotension, cardiac dysrhythmias and/or conduction blocks, and seizures is strongly advised. If signs of toxicity occur at any time during this period, extended monitoring is recommended. There are case reports of patients succumbing to fatal dysrhythmias late after overdose; these patients had clinical evidence of significant poisoning prior to death and most received inadequate gastrointestinal decontamination. Monitoring of plasma drug levels should not guide management of the patient.

12.1 Mechanism of Action

Doxepin binds with high affinity to the histamine H1 receptor (Ki < 1 nM) where it functions as an antagonist. The exact mechanism by which doxepin exerts its sleep maintenance effect is unknown but is believed due to its antagonism of the H1 receptor.

12.2 Pharmacodynamics

12.3 Pharmacokinetics

12.4. Drug Interactions

Since doxepin is metabolized by CYP2C19 and CYP2D6, inhibitors of these CYP isozymes may increase the exposure of doxepin.

12.5. Special Populations

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

14.1. Controlled Clinical Trials

The efficacy of doxepin hydrochloride tablets for improving sleep maintenance was supported by six randomized, double-blind studies up to 3 months in duration that included 1,423 subjects, 18 to 93 years of age, with chronic (N = 858) or transient (N = 565) insomnia. Doxepin hydrochloride tablets were evaluated at doses of 1 mg, 3 mg, and 6 mg relative to placebo in inpatient (sleep laboratory) and outpatient settings.

The primary efficacy measures for assessment of sleep maintenance were the objective and subjective time spent awake after sleep onset (respectively, objective Wake After Sleep Onset [WASO] and subjective WASO).

Subjects in studies of chronic insomnia were required to have at least a 3-month history of insomnia.

16.1. How Supplied

Doxepin Hydrochloride Tablets are available containing 3.39 mg or 6.78 mg of doxepin hydrochloride equivalent to 3 mg or 6 mg of doxepin, respectively.

The 3 mg tablets are blue, oval shaped, unscored tablets debossed with 3 on one side of the tablet and SP on the other side. They are available as follows:

NDC 0378-4810-93
bottles of 30 tablets

The 6 mg tablets are green, oval shaped, unscored tablets debossed with 6 on one side of the tablet and SP on the other side.

NDC 0378-4811-93
bottles of 30 tablets

16.2. Storage and Handling

Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature.]

Protect from light.

17.1. Sleep-driving and Other Complex Behaviors

There have been reports of people getting out of bed after taking a hypnotic and driving their cars while not fully awake, often with no memory of the event. If a patient experiences such an episode, it should be reported to his or her doctor immediately, since “sleep-driving” can be dangerous. This behavior is more likely to occur when a hypnotic is taken with alcohol or other central nervous system depressants [see Warnings and Precautions (5.2, 5.4) and Drug Interactions (7.3, 7.4)]. Other complex behaviors (e.g., preparing and eating food, making phone calls, or having sex) have been reported in patients who are not fully awake after taking a hypnotic. As with “sleep-driving”, patients usually do not remember these events.

In addition, patients should be advised to report all concomitant medications to the prescriber. Patients should be instructed to report events such as “sleep-driving” and other complex behaviors immediately to the prescriber.

17.2. Suicide risk and Worsening of Depression:

Patients, their families, and their caregivers should be encouraged to be alert to worsening of depression, including suicidal thoughts and actions. Such symptoms should be reported to the patient’s prescriber or health professional.

17.3. Administration Instructions

Patients should be counseled to take doxepin hydrochloride tablets within 30 minutes of bedtime and should confine their activities to those necessary to prepare for bed. Doxepin hydrochloride tablets should not be taken with or immediately after a meal [see Dosage and Administration (2.3)]. Advise patients NOT to take doxepin hydrochloride tablets when drinking alcohol [see Warnings and Precautions (5.2, 5.4) and Drug Interactions (7.3)].

17.4. Medication Guide